1. Field of the Invention
The present invention relates to a write data generating circuit in a magnetic recorder using a magnetic disc, a magnetic tape, or the like, more particularly to a write data compensating circuit which is incorporated in the write data generating circuit. The write data compensating circuit usually first determines whether the pitch between two adjacent inversions of magnetization is long or short. The pitch is determined by analyzing the binary data to be written. The circuit then preshifts the timing of the inversions of magnetization in accordance with the pitch.
2. Description of the Prior Art
In a digital magnetic recorder, it is desirable to reduce the interval between binary data to increase the amount of data stored therein. This results in a very high density of inversions of magnetization on the magnetic recording medium. It is well known that, when inversions of magnetization are formed with a very high density on a medium, the waveform of the signal reproduced from the medium often suffers from undesired distortion due to a so-called "pulse crowding effect" in which a peak shift (mentioned hereinafter) occurs.
In the prior art, at least three clock signals having the same frequency but being different in phase are used in the write data compensating circuit to cope with the pulse crowding effect. The preshift for the timing of magnetization inversions is achieved by suitably selecting one of the three clock signals in accordance with the pitch determined by the binary data to be written.
There are, however, problems with the abovementioned prior art write data compensating circuit. As will be explained in detail hereinafter, first the amount of the preshift for the magnetization inversion cannot be very large. Second, high speed logic elements must be employed in the write data compensating circuit.